[SYCL] Support sycl_khr_default_context (#15645)

Spec: KhronosGroup/SYCL-Docs#624
sycl-cts: KhronosGroup/SYCL-CTS#960

This patch is intended to be merged only when there are sycl-cts tests
and the ratified khr extension.

Author: KornevNikita

sycl/include/sycl/platform.hpp

@@ -208,6 +208,11 @@ class __SYCL_EXPORT platform : public detail::OwnerLessBase<platform> {
 
   std::vector<device> ext_oneapi_get_composite_devices() const;
 
+  /// Returns a copy of the default context object for this platform.
+  ///
+  /// \return the default context
+  context khr_get_default_context() const;
+
 private:
   ur_native_handle_t getNative() const;
 

sycl/source/detail/queue_impl.hpp

@@ -85,7 +85,7 @@ class queue_impl {
           context{createSyclObjFromImpl<device>(Device), {}, {}});
 
     ContextImplPtr DefaultContext = detail::getSyclObjImpl(
-        Device->get_platform().ext_oneapi_get_default_context());
+        Device->get_platform().khr_get_default_context());
     if (DefaultContext->isDeviceValid(Device))
       return DefaultContext;
     return detail::getSyclObjImpl(

sycl/source/feature_test.hpp.in

@@ -117,6 +117,7 @@ inline namespace _V1 {
 #define SYCL_KHR_FREE_FUNCTION_COMMANDS 1
 // In progress yet
 #define SYCL_EXT_ONEAPI_ATOMIC16 0
+#define SYCL_KHR_DEFAULT_CONTEXT 1
 
 #ifndef __has_include
 #define __has_include(x) 0

sycl/source/platform.cpp

@@ -87,10 +87,7 @@ platform::get_backend_info() const {
 
 #undef __SYCL_PARAM_TRAITS_SPEC
 
-context platform::ext_oneapi_get_default_context() const {
-  if (!detail::SYCLConfig<detail::SYCL_ENABLE_DEFAULT_CONTEXTS>::get())
-    throw std::runtime_error("SYCL default contexts are not enabled");
-
+context platform::khr_get_default_context() const {
   // Keeping the default context for platforms in the global cache to avoid
   // shared_ptr based circular dependency between platform and context classes
   std::unordered_map<detail::PlatformImplPtr, detail::ContextImplPtr>
@@ -109,6 +106,13 @@ context platform::ext_oneapi_get_default_context() const {
   return detail::createSyclObjFromImpl<context>(It->second);
 }
 
+context platform::ext_oneapi_get_default_context() const {
+  if (!detail::SYCLConfig<detail::SYCL_ENABLE_DEFAULT_CONTEXTS>::get())
+    throw std::runtime_error("SYCL default contexts are not enabled");
+
+  return khr_get_default_context();
+}
+
 std::vector<device> platform::ext_oneapi_get_composite_devices() const {
   // Only GPU architectures can be composite devices.
   auto GPUDevices = get_devices(info::device_type::gpu);

sycl/test-e2e/Basic/khr_get_default_context.cpp

@@ -0,0 +1,26 @@
+// RUN: %{build} -o %t.out
+// RUN: %{run} %t.out
+
+// Test checks that the default context contains all of the root devices that
+// are associated with this platform.
+
+#include <algorithm>
+#include <sycl/detail/core.hpp>
+
+using namespace sycl;
+
+int main() {
+  auto platforms = platform::get_platforms();
+
+  for (const auto &plt : platforms) {
+    auto def_ctx_devs = plt.khr_get_default_context().get_devices();
+    auto root_devs = plt.get_devices();
+
+    for (const auto &dev : root_devs)
+      if (std::find(def_ctx_devs.begin(), def_ctx_devs.end(), dev) ==
+          def_ctx_devs.end())
+        return 1;
+  }
+
+  return 0;
+}

sycl/test/abi/sycl_symbols_linux.dump

@@ -4025,6 +4025,7 @@ _ZNK4sycl3_V18platform13has_extensionENS0_6detail11string_viewE
 _ZNK4sycl3_V18platform16get_backend_infoINS0_4info6device15backend_versionEEENS0_6detail20is_backend_info_descIT_E11return_typeEv
 _ZNK4sycl3_V18platform16get_backend_infoINS0_4info6device7versionEEENS0_6detail20is_backend_info_descIT_E11return_typeEv
 _ZNK4sycl3_V18platform16get_backend_infoINS0_4info8platform7versionEEENS0_6detail20is_backend_info_descIT_E11return_typeEv
+_ZNK4sycl3_V18platform23khr_get_default_contextEv
 _ZNK4sycl3_V18platform30ext_oneapi_get_default_contextEv
 _ZNK4sycl3_V18platform32ext_oneapi_get_composite_devicesEv
 _ZNK4sycl3_V18platform3getEv

sycl/test/abi/sycl_symbols_windows.dump

@@ -3872,6 +3872,7 @@
 ?ext_oneapi_get_backend_content_view_impl@device_image_plain@detail@_V1@sycl@@IEBA?AU?$pair@PEBW4byte@std@@PEBW412@@std@@XZ
 ?ext_oneapi_get_composite_devices@platform@_V1@sycl@@QEBA?AV?$vector@Vdevice@_V1@sycl@@V?$allocator@Vdevice@_V1@sycl@@@std@@@std@@XZ
 ?ext_oneapi_get_default_context@platform@_V1@sycl@@QEBA?AVcontext@23@XZ
+?khr_get_default_context@platform@_V1@sycl@@QEBA?AVcontext@23@XZ
 ?ext_oneapi_get_graph@queue@_V1@sycl@@QEBA?AV?$command_graph@$0A@@experimental@oneapi@ext@23@XZ
 ?ext_oneapi_get_kernel@kernel_bundle_plain@detail@_V1@sycl@@AEAA?AVkernel@34@Vstring_view@234@@Z
 ?ext_oneapi_get_kernel@kernel_bundle_plain@detail@_V1@sycl@@QEAA?AVkernel@34@AEBV?$basic_string@DU?$char_traits@D@std@@V?$allocator@D@2@@std@@@Z

sycl/unittests/Extensions/DefaultContext.cpp

@@ -36,6 +36,9 @@ void test_default_context_enabled() {
 
   ASSERT_EQ(Dev1.get_platform().ext_oneapi_get_default_context(),
             Dev2.get_platform().ext_oneapi_get_default_context());
+
+  ASSERT_EQ(Dev1.get_platform().khr_get_default_context(),
+            Dev2.get_platform().khr_get_default_context());
 }
 
 void test_default_context_disabled() {